Where to (legally) acquire content to play on RetroPie

Auster

First and foremost, it seems both the PSP and PS2 have unique revisions of the PS1 firmware/BIOS, but I could find only how to dump the PSP version of the BIOS. I'm still trying to find a way to dump the PS2 version, but neither Google nor uLaunchelf 4.12 are being helpful with finding a way to do so.

Now, I used this process to dump the BIOS: https://www.reddit.com/r/PSP/comments/l3kn0l/better_way_to_extract_psx_bios_from_the_emulator/

A few things to note:

On step 1, I couldn't open flash0: on Linux (or it got mounted on some super random folder I couldn't find), so I suggest sticking with Windows for this one. And if you still can't open flash0: through USB, when setting the "USB device" in the "PRO VSH Menu", make sure you also open the option "Recovery Menu", go to "Configuration" and press right on "Protect flash in USB device mount" to enable it (no need to do it if it already appears as enabled). Then press select and exit the PRO VHS Menu to save.

On step 2, the kd folder and the file you want to copy in flash0: are set as system protected files, so you need to unhide them by setting hidden and system protected files to be shown in the folder/file browser options.

Also, the file you need to get has different names depending on the version of the console, but it seems it always has the name pops_0Xg.prx, where X in 0Xg changes depending on the console.

On step 4, I got the version "2.7a fix" of the PRX Decrypter.

And since the pops_0Xg.prx's hex table changes a bit from version to version, it still needs to be confirmed, but to get the BIOS itself on step 6, the steps below could help with having less variance, but make sure you still confirm the offsets that the OP mentioned after isolating the BIOS' hex table:

Open the decrypted .PRX file in a hex editor (I'm using HxD as well).
Use the editor's text search function to find "System ROM Version 4.5" (without quotation marks). Ctrl F in HxD.
Click in the beginning of the selection.
Hold shift and go up until "Lenght(h)" is at 7FF32. May take a little while, since it's a lot of data to select. Holding page up instead of the up arrow may speed things up.
Click in the beginning of the selection.
Use the text editor's select block function if it has it. If it doesn't, shift and go down until "Lenght(h)" is at 80000. HxD's default select block function can be accessed with Ctrl E, and then you need to tick the options "hex" and "Lenght:", and then write "80000" (without quotation marks) below "Lenght:".
Then copy the selection and paste in a new, empty file (Ctrl N in HxD), save the file and name it as what your emulator of choice expects. The BIOS itself doesn't seem to have any region locks, so the name just needs to match what your emulator expects (mind the name can change depending on the game's region), and you can even have multiple copies of the file, but with the required regional names.
My BIOS' md5sum, according to both Windows Subsystem for Linux and Windows' Powershell, is c53ca5908936d412331790f4426c6c33. If the BIOS doesn't change between console releases and firmware updates, yours should be the same as mine.

And lastly, when looking in the PS Vita's internal memory, I couldn't find anything that looked like it could belong to a PSP, so either the default PSP OS used in the Vita is extremely simplified so that a proper PS1 BIOS isn't included, or the firmware files are better hidden than most other files. In other words, I couldn't find a PS1 BIOS in the Vita.

Auster

It seems you can get a working PS1 BIOS from the PS3 too.

I'll try to shorten the explanation since it has multiple variations depending on what the user wants (or can) use, but hopefully what I say should be clear enough.

Install a CFW or HEN or any other OS mods that let you access the files from the PS3's other partitions.

Install a homebrew that lets you browse the internal storage and copy files elsewhere. Either Multiman/mmCM or Irisman should work. And at least Multiman should let you access the file through FTP if that's what you're going to use.

The BIOS is the file ps1_rom.bin in the folder /dev_flash/ps1emu

You need to copy this file to where you want to use it (AND NOT MOVE/REMOVE THE ORIGINAL FILE; THIS COULD BRICK YOUR CONSOLE).

If you want to use an USB stick to copy the files, first locate the file in the file browser homebrew of your choice. If you use Irisman, also locate the USB partition in the other side of the screen (it should be /dev_usb000/ or something similar). Then copy the file over to the USB partition (AGAIN, DON'T REMOVE THE ORIGINAL FILE). Then proceed to close the homebrew, turn off the PS3 and put your USB stick in your PC or another device that can read it, then copy the file over.

If you want to use FTP, first start HEN/CFW/whatever you use and make sure a homebrew with FTP function is installed. The confirm that FTP is active by going to "Settings" in the XMB, then "Network Settings", then "Settings and Connections Status List" and checking if a code appears in the line that says "IP Address". If it appears, then FTP is active, and if it doesn't, you need to enable it in your file browser (and sorry but I don't know where the setting is; I only found it once about 2 years ago). After confirming FTP is active, put that code from IP Address in your FTP client of choice, use the FTP client to go to /dev_flash/ps1emu and copy the file ps1_rom.bin over (AND ONCE MORE, DON'T REMOVE THE ORIGINAL FILE FROM THE PS3'S INTERNAL MEMORY).

After that, you just need to name the the copy you created of the file as what your emulator of choice expects and place it where the emulator wants. Don't worry about regions, as the BIOS doesn't seem to have any region locks.

I used a PS3 CECH-4011B on the firmware version 4.84 and with the HEN mod.

I don't know if this file changes much between firmware and model versions, but if it helps anyone, the md5sum of the file I got is 81bbe60ba7a3d1cea1d48c14cbcc647b, and it has this near the end of the file's HEX table: "System ROM Version 5.0 06/23/03 A".

Auster

First, I don't know if it was a coincidence or not, but if the information added to the libretro docs about the PSP's PS1 BIOS was based on what I shared, thanks to whomever did it.
I usually forget to share in other places what I post here, so, by doing it, you helped a bunch. ^_^
And on that topic, if people want to share other informations I post here, such as the list of all those Itchio games, be my guest.

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Now, more games (and an add-on):

314se add-on for AmigaOS 3.14: https://8080.itch.io/se-add-on-for-amigaos-314
Platform: AmigaOS
I don't own the add-on, but the information in the store page confirms it can be run in emulators.

[German] Crazy News: https://protovision.itch.io/german-crazy-news
Platform: Commodore 64
I don't own the game, but it probably comes with files that can be emulated, like the developers' other titles.

Mars: https://psytronik.itch.io/mars
Platforms: Commodore 64 & C64 Mini/Maxi
I don't own the game, but the information in the store page confirms it can be run in emulators.

Rayslinger: https://unicore.itch.io/rayslinger
Platforms: GameBoy consoles family
The ROM is the downloadable .gb file. And according to the store page, it's compatible with all GameBoy consoles.

Powerglove: https://rgcddev.itch.io/powerglove
Platform: Commodore 64
The C64 ROM is the .crt file from either the "C64 Binaries and VICE" or "C64 Binaries Only" download options.

Bonkey Kong: https://axtevision.itch.io/bonkey-kong
Platform: Commodore 64
The ROMs are the downloadable .tap and .d64 files.

The Legend of Weed N' Stiff: https://calgames.itch.io/the-legend-of-weed-n-stiff
Platform: NES
The ROM is the downloadable .NES file.

Mr. Maymunshine's Christmas Land: https://calgames.itch.io/mr-maymunshines-christmas-land
Platform: NES
I don't own the game, but the information in the store page confirms it can be run in emulators.

Pushingo: https://lacoste42.itch.io/pushingo
Platform: GameBoy
The ROM is the downloadable .gb file. Also includes a .cia file (3DS package installer), but it's just the GB version wrapped to run in the 3DS with its native emulator.

C-2048: https://rgcddev.itch.io/c-2048
Platform: Commodore 64
The C64 ROM is the .crt file from either the "C64 Binaries and VICE" or "C64 Binaries Only" download options.

Auster

@auster said in Where to (legally) acquire content to play on RetroPie:

To convert PSP games, just rename EBOOT.PBP's extension to .iso (also feel free to change the rest of the name). After doing it, the other file, "__sce_ebootpbp", will no longer be needed.

Turns out I was somewhat wrong regarding this.
Thanks to the recent DNS issues, the activation file for PSP/PS1 games in my console was deleted, and then none of the games would work in the Vita.
They'd still work in emulators, and redownloading a random game from my account fixed the activation issue, but helped me notice my "conversion" was wrong.
After the issue, I looked around for information, and from what I read, it seems EBOOT.PBP is a highly compressed disc image, and for PSP games, this compression can take up to half of the original disc's size.
To properly convert/uncompress the files, turns out I had to use this program: https://sites.google.com/site/theleecherman/IsoPbpConverter
...Which was hard to find, with so much noise in the search results.
But anyways, download it, unpack, open the executable (tested on Linux with Wine so it should work in multiple platforms), click in the button to the right of "Input Iso/Pbp", open your EBOOT.PBP file, click in the floppy disc icon and choose an output folder and name (the default is the game's ID with the .ISO extension, all caps).
After the conversion is complete (may take some minutes), the program will say "dumping complete" and you'll have in the output folder a file bigger than your original EBOOT.PBP file and that should work anywhere.

Auster

@auster said in Where to (legally) acquire content to play on RetroPie:

The Seance: https://quantumsheep.itch.io/the-seance
Platform: ZX Spectrum

&

Main Course - The Retro Cut: https://quantumsheep.itch.io/main-course-the-retro-cut
Platform: ZX Spectrum

Platform added: Sharp MZ-80A
The Sharp MZ-80A ROMs for both are the downloadable .mzf files.

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Morpheus: https://insighted.itch.io/morpheus
Platform: GameBoy Advance/GBA & Nintendo DS/NDS
Engine for making GBA and NDS games, and also includes some prototype ROMs (.gba for GBA and .nds for Nintendo DS, both inside the /tests/ folder in either downloadable .zip files). Also appears to be open source, but I suggest asking the dev what are the limitations of the project.

Coria and the Sunken City (demo, at least for now): https://coria.itch.io/coria
Platform: GameBoy
The ROM is the downloadable .gb file.

Wink GameBoy: https://maxoakland.itch.io/wink-gameboy
Platforms: GameBoy and GameBoy Color/GBC
The GameBoy ROM is the .gb file inside the downloadable .zip file. The GBC ROM is the the downloadable .gbc file.

Ghoul Grind: Night of the Necromancer (demo, at least for now): https://woogworx.itch.io/ghoul-grind-night-of-the-necromancer-demo
Platforms: NES
The ROM is the .nes file inside the downloadable .zip file.

The Farm: https://lacoste42.itch.io/the-farm
Platform: GameBoy
The ROM is the downloadable .gb file. Also includes a .cia file (3DS package installer), but it's just the GB version wrapped to run in the 3DS with its native emulator.

PaperMario6.4: https://therurik.itch.io/papermario6dot4
Platform: GameBoy
The downloadable file is a GB Studio project and needs to be compiled with it. Also appears to be open source, but I suggest asking the dev what are the limitations of the project.

Auster

I also found a PS1 BIOS in my PS2's BIOS, and again it requires grabbing the code with a hex editor.

I tested with the a console that's from either Hong Kong or Japan (not sure which because the PS2 BIOS I dumped has multiple mentions of "HK" in the file names, but Retroarch says the version is "Japan v02.20"). And I'm not sure if the process changes with other versions of the BIOS, as I don't have access to other models of the PS2 to test.

On the process itself, what you want to do first is to dump the PS2 BIOS like you'd do for PS2 emulation. You can get the BIOS dumper from PCSX2's site, and make sure you read README.txt that comes with the dumper, as it has instructions on how to use the dumper.

After you dumped the BIOS, move them to your PC and open the BIOS file with a hex editor of your choice (tested with HxD; also checked with Okteta but it has some variations in the values). The file from my PS2 that has the PS1 BIOS is "SCPH-77006_BIOS_VX_HK _220.BIN", but if you're not sure about yours, open all files you dumped in the hex editor and use the search function to look for "System ROM Version" (without quotation marks). The file that has this piece of text is the one with the PS1 BIOS.

Then go to the very beginning of the file's hex table (ctrl home should work) and select an interval/lenght of either 80000 (on HxD) or 7FFFF (on Okteta) starting from there. Then copy the selection, paste in a new file and save it. The name can be whatever, as long as the emulator can read it (so for Beetle PSX, for example, it'd be something like scph550X.bin, with X being the number of the region, 0 for NTSC, 1 for NTSC-J and 2 for PAL). And if in doubt about the offsets, starting from right before "System ROM Version" and going backwards, the beginning of the BIOS should be at an offset of 7FF32 on HxD and 7FF31 on Okteta.

And as final notes, the BIOS appears to have region locks. Mine, for example, can only load NTSC-J games. And my specific BIOS has a md5sum of b2330a585d08a3fcaf8a1ca9ae08cbe3 and says "System ROM Version 5.0 02/10/06 J" in the end of the file, but if the BIOS changes depending on the console model and region, these values could also change.

Little update: I can find no information about this BIOS specifically. I'll ask around to see what name convention people could use, if they want to share the information I brought here. But in the meantime, I'll be calling it "SCPH77006.BIN".

Auster

Did anyone manage to get working files out of Wings on GOG and Sonic Adventure DX on Steam?

With Wings, I tried extracting it with tools such as 7z and Unzip, and the only file I got that I managed to identify is the Workbench v1.2 file, and not the game itself.

And with Sonic DX, I tried using the romextract tool without success.

Auster

@auster said in Where to (legally) acquire content to play on RetroPie:

Did anyone manage to get working files out of Wings on GOG and Sonic Adventure DX on Steam?

With Wings, I tried extracting it with tools such as 7z and Unzip, and the only file I got that I managed to identify is the Workbench v1.2 file, and not the game itself.

And with Sonic DX, I tried using the romextract tool without success.

About Wings, an user in another forum helped me find a way to extract the Commodore Amiga ROMs:
https://github.com/sigboe/extractwings

Also, if you're on Linux/WSL, you can change the first command of the tutorial above to this if you want the Kickstart 1.2 BIOS:

7z e -tzip -aos Wings.exe Kick12.rom -r

You can probably get the Kickstart file with a GUI-based program such as Windows' 7zip as well.

The Kickstart's md5sum should match the one listed in the BIOS part of PUAE's page on Libretro/Retroarch's site. Then you just need to rename it for what your emulator of choice expects.

Clyde

@auster Wow, thanks to you and to sigboe on Github! 👍

Auster

neMULEsis: https://johnvanderhoef.itch.io/nemulesis
Platform: NES
The ROM is the downloadable .nes file.

Blockade: https://lacoste42.itch.io/blockade
Platform: GameBoy
The ROM is the downloadable .gb file. Also includes the source code, but I suggest asking the dev what are the limitations of the project.

ADVENTURES CONTINUE ZX Spectrum 48/128k: https://pcnonogames.itch.io/adventures-continue-zx-spectrum-48128k
Platforms: ZX Spectrum 48k/128k
I don't own the game, but the information in the store page confirms it can be run in emulators.

Transylvanian Castle 2 - The Eye of Velnor: https://siyei-er.itch.io/transylvanian-castle-2-the-eye-of-velnor
Platforms: ZX Spectrum
The ROMs are the .tap files inside each downloadable .rar file. ROMs are on either English, Spanish or Portuguese (languages specified in each download option).

SORCERY ISLAND: https://manuel-gris-umpierrez.itch.io/sorcery-island
Platform: ZX Spectrum 48K
The ROMs are the .tap files inside each downloadable .rar file. ROMs are on either English or Spanish (languages specified in each download option).

Nevermore: https://ejvg.itch.io/nevermore
Platform: ZX Spectrum
The ROMs are the downloadable .tap and .tzx files. ROMs are on either English, Spanish or Portuguese (languages specified in each download option).

Hollow Knight Silksong [Gameboy Demake]: https://elvies.itch.io/silksongdemake
Platforms: GameBoy | GameBoy Color/GBC | GameBoy Advanced/GBA
The GameBoy ROM is the downloadable .gb file. The GBC ROM is the downloadable .gbc file. The GBA ROM is the downloadable .gba file.

SPACE SAMURAI: https://zanilo.itch.io/space-samurai
Platform: GameBoy
The ROM is the downloadable .gb file.

windsor road: https://everydaylouie.itch.io/windsor-road
Platform: GameBoy
The ROM is the downloadable .gb file.

Project Trap: https://elvies.itch.io/projecttrap
Platform: GameBoy
The ROMs are the downloadable .gb files.

Auster

Indiana Jones and the Fate of Atlantis is included on Amazon Prime this month, and it can be run on either ScummVM or DOSBox, but a file needs to be extracted before it can be run.

First, download the game with the Prime Gaming launcher and go to the folder where you downloaded the game.

If you're using either Linux or a WSL, run either of these commands from the game's root folder (where "Indiana Jones and the Fate of Atlantis.exe" and "testapp.exe" are):

dd if="Indiana Jones and the Fate of Atlantis.exe" of=ATLANTIS.000 bs=1 skip=224336 count=12035

dd if=testapp.exe of=ATLANTIS.000 bs=1 skip=224336 count=12035

And if you're using Windows commands, first download these files and place them in the root folder of the game:
https://github.com/sigboe/extractwings/blob/master/dd.exe
https://github.com/sigboe/extractwings/blob/master/libiconv2.dll
https://github.com/sigboe/extractwings/blob/master/libintl3.dll

Then run a command in the folder where you placed the 3 files.

On CMD, it can be either of those:

".\dd.exe" "if=.\Indiana Jones and the Fate of Atlantis.exe" "of=.\ATLANTIS.000" bs=1 skip=224336 count=12035

".\dd.exe" "if=.\testapp.exe" "of=.\ATLANTIS.000" bs=1 skip=224336 count=12035

On PowerShell, it can be either of those:

 .\dd.exe if=.\"Indiana Jones and the Fate of Atlantis.exe" of=.\ATLANTIS.000 bs=1 skip=224336 count=12035

.\dd.exe if=.\testapp.exe of=.\ATLANTIS.000 bs=1 skip=224336 count=12035

All commands will output the same file. And if you want to make sure, these are their sha1sum hashes:
f836e9d15490955d22b6f88072c55fb6b751dc10 Indiana Jones and the Fate of Atlantis.exe
f836e9d15490955d22b6f88072c55fb6b751dc10 testapp.exe
47b11368ae266ac6f8a48e781d6eb274531a6e35 ATLANTIS.000

After extracting the file, if you want to run the game on DOSBox, just place the extracted "ATLANTIS.000" file inside the folder ATLANTIS inside the game's folder, then run ATLANTIS.EXE with DOSBox.

If you want to play it on ScummVM, you only need ATLANTIS.000, ATLANTIS.001 and MONSTER.SOU in the same folder, then point ScummVM to the folder where the files are. And Retroarch can launch the game from any of the 3 files.

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On a side note, if anyone has the Humble Trove version of the game backed up (it's no longer available for download), getting the files from the Windows version should be the same as with the Prime version, while it should be much easier to get the files with the MacOS version.

The game folder with the needed files is in the Windows version, after you install it, is in C: > Program Files (x86) > Lucasfilm Ltd Disney > Indiana Jones and the Fate of Atlantis

To get these files in the MacOS version, extract the Indiana_Jones_and_the_Fate_of_Atlantis_1547160339.zip file and go to the folder Indiana Jones and the Fate of Atlantis.app > Contents > Resources > game > game. All 3 ScummVM files are ready to be used there already, and if you want to run on DOSBox, just copy the ScummVM files to the folder "other" that's besides them, then run ATLANTIS.EXE with DOSBox.

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And lastly, I didn't test the Steam or GOG versions.

Auster

According to a thread in the Steam forum, Demons of Asteborg includes a Sega Genesis/Mega Drive ROM, but with some caveats:

Comment #3:

looks like Rom is included in the game folder and the base of this game.

Comment #4:

yes is the rom file. only works on BlastEm currently. needs to be altered. header needs to be changed and one byte removed. no flashcard works cause of the big size of the game, this needs a new Mapper. infos on this on some Twitter Threads with the devs.

I don't have the game in my account, so I can't confirm.

Auster

Hollow Knight Beta [Gameboy Demake] - https://elvies.itch.io/hollowknightdemake
Platforms: GameBoy | GameBoy Color/GBC | GameBoy Advanced/GBA
The GameBoy and GBC ROMs are the downloadable .gb files. The GBA ROMs are the downloadable .gba file.

For MXR Plays & Potasticpanda - https://elvies.itch.io/astra-prom-wholesome-panda-version
Platform: GameBoy
I don't own the game, but the information in the game page confirms it can be emulated, and that it includes the G Studio project as well.

El experimento - https://ejvg.itch.io/el-experimento
Platform: ZX Spectrum 128K
The ROM is the .tap file inside the downloadable .zip file.

Farila(TALPES) - https://ejvg.itch.io/farilatalpes
Platform: ZX Spectrum 128K
The ROMs are the .tap and .z80 files inside the downloadable .zip file.

Los archivos de Gost-Soft - https://ejvg.itch.io/los-archivos-de-gost-soft
Platform: ZX Spectrum
The ROMs are the downloadable .tzx and .z80 files.

Puta mili / Fucking mili - https://ejvg.itch.io/puta-mili
Platform: ZX Spectrum 48K
The ROMs are the .tap files inside the each downloadable .zip file.

Wudang - https://worldxxisoft.itch.io/wudang
Platform: ZX Spectrum 48K
The ROMs are the .tap, .dsk, .scl, .trd and .tzx files inside the downloadable .zip file.

Redshift - https://worldxxisoft.itch.io/redshift/
Platform: ZX Spectrum 128K
The ROMs are the .tap, .dsk, .scl, .trd and .tzx files inside the downloadable .zip file.

Carlos Michelis - https://worldxxisoft.itch.io/carlos-michelis
Platform: ZX Spectrum
I don't own the full game, but by the files in the demo and the information in the store page, it can be emulated. The ROMs from the demo are the .scl, .tap, .trd and .tzx files.

Escuela de Ladrones / Thieves School - https://worldxxisoft.itch.io/escuela-de-ladrones-thieves-school
Platform: ZX Spectrum
I don't own the full game, but by the files in the demo and the information in the store page, it can be emulated. The ROMs from the demo are the downloadable .tap file and the .trd file inside the downloadable .zip file.

Max Pickles I - https://worldxxisoft.itch.io/max-pickles-i
Platform: ZX Spectrum
The ROMs are the .tap, .dsk, .scl, .trd and .tzx files inside the downloadable .zip file.

Max Pickles II - https://worldxxisoft.itch.io/max-pickles-ii
Platform: ZX Spectrum
The ROMs are the .tap, .dsk, .scl, .trd and .tzx files inside the downloadable .zip file.

Max Pickles III - https://worldxxisoft.itch.io/max-pickles-iii
Platform: ZX Spectrum
The ROMs are the .tap, .dsk, .scl, .trd and .tzx files inside the downloadable .zip file.

Callemanía / Streetmania 2008 - https://worldxxisoft.itch.io/callemana-streetmania-2008
Platform: ZX Spectrum
The ROM is the .z80 file inside the downloadable .zip file.

G.I.Tech - https://worldxxisoft.itch.io/gitech
Platform: ZX Spectrum
The ROM is the .tzx file inside the downloadable .zip file.

Galactron - https://worldxxisoft.itch.io/galactron
Platform: ZX Spectrum
The ROM is the .z80 file inside the downloadable .zip file.

Infierno Azul / Blue Hellfire - https://worldxxisoft.itch.io/infierno-azul-blue-hellfire
Platform: ZX Spectrum
The ROMs are the .trd and .tzx files inside the downloadable .zip file.

Off Shore Racing - https://worldxxisoft.itch.io/off-shore-racing
Platform: ZX Spectrum
The ROM is the .tzx file inside the downloadable .zip file.

mitu

@auster said in Where to (legally) acquire content to play on RetroPie:

According to a thread in the Steam forum, Demons of Asteborg includes a Sega Genesis/Mega Drive ROM, but with some caveats:
[...]

See https://retropie.org.uk/forum/topic/31088/, it's probably going to be supported by more emulators at some point.

Auster

Back in June, both Syndicate games and Ultima Underworld 1 and 2 (all MS-DOS games) were removed from GOG, and apparently from Origin too.

Now it seems they're back, and at least the GOG titles are 100% off for a limited time. And the games on Origin are free as well, but I couldn't find info confirming it's a temporary free there (they were paid before being removed, so it wouldn't hurt to claim them as well).

GOG sale of these games:
https://www.gog.com/promo/rerelease_ultima_underworld_and_syndicate
Which includes:
https://www.gog.com/game/ultima_underworld_1_2
https://www.gog.com/game/syndicate
https://www.gog.com/game/syndicate_wars

Origin's titles:
https://www.origin.com/store/syndicate/syndicate-1993
https://www.origin.com/store/ultima/ultima-underworld-ii-labyrinth-of-worlds
https://www.origin.com/store/ultima/ultima-underworld-the-stygian-abyss

Apparently Syndicate (Origin) is the original version while Syndicate Plus (GOG) is an expanded version, and it seems Syndicate Wars is only available on GOG.

If anyone has trouble launching Ultima Underworld 1 and 2, the GOG and Origin versions have different steps.

For Origin, create a .bat file with a name not directly related to the games inside each game's DATA folders (default on Windows is C: > Program Files (x86) > Origin Games > [game's name] > DATA), then paste these scripts inside them:

For Ultima Underworld 1:

imgmount d game.dat -t iso -fs iso
cls
d:
uw.bat

For Ultima Underworld 2:

imgmount d game.dat -t iso -fs iso
d:
cls
uw2.bat

For the GOG version, rename dosboxULTIMA1_single.conf (for the 1st game) and dosboxULTIMA2_single.conf (for the 2nd game) as .bat files (again, names not directly related to the games). They should be kept in their game's root folders (where they already were).

Then launch the games from these .bat files. And if DOSBox returns an "illegal command" error, try to shorten the name of the .bat files.

Crush

Thanks for alerting us of the free games, i didnt have ultima yet.
I deff advice anyone to get the Syndicate games while they're still available for free, they're really good. Played them to death back in the days. and again last year.
Shame to see them go.
https://www.gog.com/promo/rerelease_ultima_underworld_and_syndicate

HipsterElephant

Here's two that I've been having a ton of fun with (one you have to pay for, the other is free)

Xeno Crisis, a twinstick shooter for Genesis/Mega Drive (well, more like dual + + genesis interface but you get the idea), as well as Dreamcast and Neo Geo (AES and CD)
https://shop.bitmapbureau.com/collections/sega-mega-drive-genesis/products/xeno-crisis-sega-mega-drive-genesis-rom-download
(it's the devs store)

next is Pyoro64 for the Nintendo 64, a remake of the minigame you find in WarioWare
Here's footage from the original game

here's footage from the 64 remake

the 64 remake runs great on the Pi.

DL:
https://n64squid.com/pyoro-64/

Auster

BlindJump - https://evanbowman.itch.io/blindjump
Platforms: GameBoy Advance/GBA | PlayStation Portable/PSP
The GBA version comes already compiled and is the downloadable .gba file. The PSP version needs to be compiled from source and currently has no audio. Also, the game is open source.

Skyland - https://evanbowman.itch.io/skyland
Platform: GameBoy Advance/GBA
Download the precompiled .gba ROM from either Itchio or Github, or build it yourself. Also open source.

Fireman - https://lacoste42.itch.io/fireman
Platform: GameBoy Color/GBC
The ROM is the downloadable .gbc file. Also includes the GB Studio source code, but no license is included, so you may want to ask the dev what are the conditions for use.

Tales of Monsterland (demo, at least for now) - https://joelj.itch.io/talesofmonsterland
Platform: GameBoy
The ROM is the downloadable .gb file.

GBCOMPO21 Entry - https://skittlesfiddles.itch.io/gbcompo21-entry
Platform: GameBoy
The ROMs are the downloadable .gb file.

GBJAMRB - https://skittlesfiddles.itch.io/gbjamrb
Platform: GameBoy
The ROM is the downloadable .gb file.

Repugnant Bounty RetroBreak Build #1 - https://skittlesfiddles.itch.io/repugnant-bounty-retrobreak-build-1
Platform: GameBoy Color/GBC
The ROM is the downloadable .gb file.

Repugnant Bounty RetroBreak Build #2 - https://skittlesfiddles.itch.io/repugnant-bounty-retrobreak-build-2
Platform: GameBoy Color/GBC
The ROM is the downloadable .gb file.

Repugnant Bounty RetroBreak Build #3 - https://skittlesfiddles.itch.io/repugnant-bounty-retrobreak-build-3
Platform: GameBoy Color/GBC
The ROM is the downloadable .gb file.

LUNA (Build Dumps) - https://skittlesfiddles.itch.io/luna-final-build
Platform: GameBoy
Canceled game. The ROMs are the downloadable .gb file.

Auster

NES-Pong - https://jamessheppard.itch.io/nes-pong
Platform: NES
The ROM is the downloadable .nes file.

Temple Dilemma (demo, at least for now) - https://weapon121.itch.io/temple-dilemma
Platform: NES
The ROM is the downloadable .nes file.

Caged Fury - https://weapon121.itch.io/caged-fury
Platform: NES
The ROM is the .nes file inside the downloadable .zip file.

Thunder Paw (demo, at least for now) - https://pscdgames.itch.io/thunder-paw
Platform: Sega Genesis/Mega Drive
The ROM is the .bin file inside the downloadable .7z file.

Bone Marrow Rebirth (demo, at least for now) - https://pscdgames.itch.io/bone-marrow
Platform: Sega Genesis/Mega Drive
The ROM is the .bin file inside the downloadable .7z file.

FIRE AND RESCUE - https://skyboygames.itch.io/fire-and-rescue
Platform: NES
I don't own the game, but the information in the store page confirms it can be run on an emulator.

ITALIA 1944 - https://zanklesoft.itch.io/italia-1944
Platform: ZX Spectrum 48K
I don't own the game, but it likely comes with files that can be emulated.

COUSIN HORACE - https://zanklesoft.itch.io/cousin-horace
Platform: ZX Spectrum (48K/128K)
I don't own the game, but it likely comes with files that can be emulated.

AD LUNAM COLLECTION - https://zanklesoft.itch.io/ad-lunam-collection
Platform: ZX Spectrum (48K/128K)
I don't own the game, but it likely comes with files that can be emulated.

SOPHIA - https://zanklesoft.itch.io/sophia
Platform: ZX Spectrum 128K
The ROMs are the .scl, .trd and .tap files inside the downloadable .zip file.

SOPHIA II - https://zanklesoft.itch.io/sophia-ii
Platform: ZX Spectrum 128K
The ROMs are the .scl, .trd and .tap files inside the downloadable .zip file.

APULIJA-13 - https://zanklesoft.itch.io/apulija-13
Platform: ZX Spectrum (48K/128K)
The ROMs are the .tap files inside each downloadable .zip file (aside from MANUALE-MANUAL.zip, which only has the manual).

LOST IN MY SPECTRUM - https://zanklesoft.itch.io/lims
Platform: ZX Spectrum (48K/128K)
The ROMs are the .tap files inside each downloadable .zip file (aside from MANUALE-MANUAL.zip, which only has the manual).

HipsterElephant

@auster said in Where to (legally) acquire content to play on RetroPie:

Skyland - https://evanbowman.itch.io/skyland
Platform: GameBoy Advance/GBA
Download the precompiled .gba ROM from either Itchio or Github, or build it yourself. Also open source.

What hooked me the most was the Gameboy Player Rumble support. I wish more games did that.